The present invention relates to a method of producing a clothing like a natural fiber denim or a denim-like clothing with worn-out feeling.
In some conventional denim-like cloths and sewn fabrics, part of the clothes or fabrics such as a projection is whitened due to repeated washing or wearing. However, these denim-like cloths and sewn fabrics mainly comprise natural fibers, are heavy, are easily ripped and are significantly discolored by action of washing.
In contrast, polyester fibers, for example, are lightweight, are resistant to ripping and are colorfast against washing. However, no proposal has been made on cloths or sewn fabrics that are fully composed of synthetic fibers and exhibit the feeling of a natural fiber denim and on sewn fabrics like a natural fiber denim.
After intensive investigations under these circumstances, the present inventors found that, when a clothing composed of a cloth comprising fibers capable of forming ultrafine fibers is subjected to flexing or rubbing to thereby induce whitening of projections of the cloth, the resulting cloth becomes like a natural fiber denim. The present invention has been accomplished based on these findings.
Separately, Japanese Examined Patent Application Publication No. 59-53945, Japanese Unexamined Patent Application Publications No. 56-148963, No. 57-143567 and No. 59-130361 propose techniques, in which a polyester fiber cloth having a multicore structure is treated with an alkali and is converted into ultrafine fibers to thereby exhibit soft feeling. In these techniques, the polyester matrix component is pretreated with an acid, and the treated polyester matrix component can be readily removed by the alkali-treatment. In other words, the publications each propose techniques to enhance the conversion of the multicore fiber into ultrafine fibers. However, these acid treatments are performed as a pretreatment operations prior to the alkali-treatment and are not concerned with a technical idea for the production of a denim-like clothing.
Accordingly, an object of the present invention is to provide a clothing like a natural fiber denim, which comprises synthetic fibers as materials but exhibits the feeling or semblance of a natural fiber denim. In addition to the above feature, this clothing has inherent advantages of a cloth made of synthetic fibers. Specifically, the clothing is lightweight, is resistant to ripping and is colorfast against washing.
Another object of the present invention is to provide a method of producing a denim-like clothing from synthetic fibers fully utilizing the characteristics of conjugated fibers. The resulting denim-like clothing exhibits the feeling or semblance of a natural fiber denim or of a stonewashed fabric.
To achieve the above objects, the present invention employs the following means.
Specifically, the present invention provides a denim-like clothing mainly including a woven or knitted fabric and having a whitening index of less than or equal to Class 4. The woven or knitted fabric comprises ultrafine fibers or fibers capable of forming ultrafine fibers on its surface, and the whitening index is expressed in a grey scale for assessing change in color specified in Japanese Industrial Standards (JIS). In preferred embodiments, the denim-like clothing has the following characteristics:
(a) the denim-like clothing has a roughness index of equal to or more than 3 micrometers as determined using a measuring machine, KES-FB4;
(b) the woven or knitted fabric is one selected from woven or knitted fabrics of modified structures, such as voile, mat USU (mat worsted), jacquard, corduroy, amunzen, cord and pile stitch;
(c) the woven or knitted fabric is produced by sewing a woven or knitted fabric having no roughness on its surface, such as taffeta, poplin, grey sheeting or SMOOTHNESS (interlock fabric) to thereby yield a sewn fabric exhibiting rough feeling on its surface;
(d) the ultrafine fibers or the fibers capable of forming ultrafine fibers are ultrafine fibers having a fineness of less than or equal to 0.6 dtex or fibers capable of in forming ultrafine fibers having a fineness of less than or equal to 0.6 dtex;
(e) the fibers capable of forming ultrafine fibers are multicore fibers;
(f) the fibers comprise, as a matrix component, a polyester containing from 1.5% to 15% by mole of a xe2x80x94SO3M group, where M is a hydrogen atom, an alkaline metal or an alkaline-earth metal;
(g) the matrix component has been treated with an acid;
(h) the multicore fibers each comprise different components, and the different components act as a matrix component with respect to each other and can be separated from each other; or
(i) the denim-like clothing readily exhibits worn-out feeling by flexing or rubbing.
The denim-like clothing is sewn by a conventional technique, and at least part of the resulting sewn fabric is whitened and exhibits the feeling or semblance of a natural fiber denim.
The denim-like clothing is preferably produced, for example, by a method in which a woven or knitted fabric including ultrafine fibers or fibers capable of forming ultrafine fibers on its surface is treated with an acidic solution with pH of from 1.5 to 4 at temperatures from 100xc2x0 C. to 140xc2x0 C., and the treated woven or knitted fabric is subjected to a combination of a flexing or rubbing step and a colored step.
The above-produced denim-like clothing is whitened due to the ultrafine fibers or the fibers capable of forming ultrafine fibers on its surface and exhibits the feeling or semblance of a natural fiber denim.